Failure Analysis of a Bellow Due to Undersized Welds

One client provided us with a pair of bellows that had cracks in the welds. Our mounting, polishing, and metallographic analysis of four sections from each assembly revealed that all eight locations failed to meet the customer-supplied fillet angle requirements.

Six of the eight locations failed to meet weld size requirements. We also found nearly invisible cracks originating at the weld root in areas where no visible cracks could be seen.

Since there were no other signs of stress that could be linked to other sources, it became clear that undersized welds were the root cause of the problem. With optical stereoscopes and a scanning electron microscope (SEM), we quickly confirmed our findings. For additional examples, download our Failure Analysis Case Stude Guide